Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S933729AbeAHTt7 (ORCPT <rfc822;ralf@linux-mips.org> + 1 other);
        Mon, 8 Jan 2018 14:49:59 -0500
Received: from mail-wr0-f178.google.com ([209.85.128.178]:38164 "EHLO
        mail-wr0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S932750AbeAHTt4 (ORCPT
        <rfc822;linux-kernel@vger.kernel.org>);
        Mon, 8 Jan 2018 14:49:56 -0500
X-Google-Smtp-Source: ACJfBotbRUZlEyhr3M2sg/TxYvysdRZKopBGBB5IdbkThzrb4WQUmyD4fe/aZ8FwvfpAMUHHd00VFA==
Date: Mon, 8 Jan 2018 12:49:50 -0700
From: Jason Gunthorpe <jgg@ziepe.ca>
To: Christoph Hellwig <hch@lst.de>
Cc: Logan Gunthorpe <logang@deltatee.com>,
        open list <linux-kernel@vger.kernel.org>,
        linux-pci@vger.kernel.org, linux-nvme@lists.infradead.org,
        linux-rdma <linux-rdma@vger.kernel.org>,
        linux-nvdimm@lists.01.org, linux-block@vger.kernel.org,
        Stephen Bates <sbates@raithlin.com>,
        Jens Axboe <axboe@kernel.dk>,
        Keith Busch <keith.busch@intel.com>,
        Sagi Grimberg <sagi@grimberg.me>,
        Bjorn Helgaas <bhelgaas@google.com>,
        Max Gurtovoy <maxg@mellanox.com>,
        Dan Williams <dan.j.williams@intel.com>,
        =?utf-8?B?SsOpcsO0bWU=?= Glisse <jglisse@redhat.com>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>
Subject: Re: [PATCH 06/12] IB/core: Add optional PCI P2P flag to
 rdma_rw_ctx_[init|destroy]()
Message-ID: <20180108194950.GK11348@ziepe.ca>
References: <20180104192225.GS11348@ziepe.ca>
 <1f8fb3fb-e3dc-94d3-e837-0cd942cf5b87@deltatee.com>
 <20180104221337.GV11348@ziepe.ca>
 <3e8391a9-8924-be6d-8c43-162a360d75b6@deltatee.com>
 <20180105045031.GX11348@ziepe.ca>
 <20180108145901.GA10743@lst.de>
 <20180108180917.GF11348@ziepe.ca>
 <20180108183434.GA15549@lst.de>
 <cffacbee-477a-fbe9-19cc-373cd2ec6fef@deltatee.com>
 <20180108185743.GA15936@lst.de>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20180108185743.GA15936@lst.de>
X-Originating-IP: [70.74.179.152]
User-Agent: Mutt/1.5.24 (2015-08-30)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org
Return-Path: <linux-kernel-owner@vger.kernel.org>

On Mon, Jan 8, 2018 at 11:57 AM, Christoph Hellwig <hch@lst.de> wrote:

>> (c) setup/manage any security permissions on mappings
>> Which P2P may at some point be concerned with.
>
> Maybe once root complexes with iommus actually support P2P.  But until
> then we have a lot more more important problems to solve.

Pretty sure P2P capable IOMMU hardware exists.

With SOC's we also have the scenario that an DMA originated from an
on-die device wishes to target an off-die PCI BAR (through the IOMMU),
that definitely exists today, and people care about it :)

Jason